Inhibition of hepatic phosphatidylcholine synthesis by malathion in rats.

Rats maintained on a 20% casein diet were given malathion orally throughout the feeding period (100 mg/kg body weight/day, dissolved in groundnut oil). Hepatic choline kinase (EC 2.7.1.32) and cholinephosphate cytidyltransferase (EC 2.7.7.15) activities were inhibited, whereas cholinephosphotransferase (EC 2.7.8.2) activity was not affected by malathion administration. Incorporation of [methyl-14C]L-methionine into hepatic microsomal phosphatidylcholine was significantly reduced by malathion administration.